A Day in the Life

David Marrett, Murrieta High School, Murrieta Valley Unified School District

Overview

Students practice simple data collection, tabulation, graphing, and analysis in this energy awareness exercise. Next, they design a conservation plan. Finally, they study how to implement the plan.

Objectives: Before effective conservation of resources can start, people need a good awareness of resource consumption patterns, including their own. This exercise will build awareness first then plan for conservation.

Subjects: Environmental Science, Earth Science, Physics

Suggested Grade Level: 10-12

California Standards Addressed: Laws of thermodynamics, especially first and second laws (1st= conservation of energy; 2nd=entropy)

Time: 6.5 hour lesson segments over 3 weeks

Materials

Notebook

Access to Internet for Research

Preparation and Background

As part of a unit on natural resource conservation, students learn the laws of thermodynamics that any "change" requires energy, energy is conserved, but constantly transformed and that nature moves toward higher disorder (entropy).

Procedure

Students note all "changes" and energy sources during one school day (6:30am to 9:00pm). Tabulate data and research sources of energy involved. All energy units will be converted to kilo joules (kJ)

For Discussion

After students submit first draft reports, energy expenditures are classified as falling into 1 of 3 categories:

Absolutely necessary

Convenient and useful, but not really needed

Wasteful

In small groups, then reporting out to the whole class, discuss how perceptions differ among the same activities.

Extensions

Each student writes an energy saving plan, calculating percentages. Students then attempt implementation and monitor successes and challenges.

Resources

Common Household Appliance Energy Use

Listed below are some common appliances, their wattage and an estimate of operating costs.

Appliance

Watts

Hours/Mo

kWh/Mo

Avg. $/Mo

Air Conditioner (Room) 6,000 BTU

750

120 – 720

90 – 540

6.75 – 40.50

Air Conditioner (Room) 9,000 BTU

1050

120 – 720

126 – 756

9.45 – 56.70

Air Conditioner (Central) 2.5 Tons

3500

240 – 860

850 – 3000

63.75 – 225.00

Can Opener

175

1/12 – 1

0.01 – 0.18

0.00 – 0.01

Ceiling Fan

60

15 – 330

1 – 20

0.08 – 1.50

Clock

5

720

4

0.30

Clothes Dryer

5000

6 – 28

30 – 140

2.25 – 10.50

Clothes Washer, Automatic (With Electric Water Heating)

500

7 – 40

33 – 196

2.48 – 14.70

Clothes Washer, Automatic (With Non-Electric Water Heating)

500

7 – 40

3 – 16

0.23 – 1.20

Coffee Maker

900

4 – 30

4 – 27

0.30 – 2.03

Computer (Monitor & Printer)

200

25 – 160

5 – 32

0.38 -2.40

Dehumidifier

350

120 – 720

42 – 252

3.15 – 18.90

Dishwasher (With Electric Water Heating)

1300

8 – 40

20 – 102

1.50 – 7.65

Dishwasher (With Non-Electric Water Heating)

1300

8 – 40

3 – 16

0.23 – 1.20

Drill

300

3 – 7

1 – 2

0.08 – 0.15

Electric Blanket

180

30 – 90

5 – 16

0.38 – 1.20

Electric Heater (Portable)

1200

30 – 90

30 – 90

2.25 – 6.75

Fan (Portable)

115

18 – 52

2 – 6

0.15 – 0.45

Food Blender

390

3 – 5

1 – 2

0.08 – 0.15

Food Freezer (15 cu. ft.)

335

180 – 420

60 – 140

4.50 – 10.50

Frying Pan

1150

10 – 20

12 – 23

0.90 – 1.73

Furnace Fan Motor (Intermittent)

350

160 – 415

56 – 145

4.20 – 10.88

Furnace Fan Motor (Continuous)

350

720

252

18.90

Hair Dryer (Portable)

1000

1 – 10

1 – 10

0.08 – 0.75

Heating Pad

65

15 – 30

1 – 2

0.08 – 0.15

Humidifier (Portable)

100

80 – 540

8 – 54

0.60 – 4.05

Iron (Hand)

1000

1 – 10

1 – 10

0.08 – 0.75

Lighting Single Lamp (60W)

60

17 – 200

1 – 12

0.08 – 0.90

Compact Fluorescent (60W Equiv)

18

17 – 200

0.3 – 3.6

0.02 – 0.27

Ceiling Fixture (3 bulbs)

180

6 – 195

2 – 35

0.15 – 2.63

Tri-Light (Table Lamp)

100

10 – 200

1 – 20

0.08 – 1.5

Chandelier (5 Lamp)

300

10 – 183

3 – 55

0.23 – 4.13

Fluorescent (2 Tube 4 ft.)

100

10 – 200

1 – 20

0.08 – 1.50

Microwave Oven

1300

5 – 30

5 – 30

0.38 – 2.25

Power Saw

275

2 – 4

0.6 – 1

0.05 – 0.08

Range

12500

10 – 50

125 – 625

9.38 – 46.88

Range (Self Cleaning Cycle Only)

3200

1/2 – 1 1/2

2 – 5

0.15 – 0.38

Refrigerator-Freezer Frost Free (17 cu. ft.)

500

150 – 300

75 – 150

5.63 – 11.25

Refrigerator (Non Frost Free, 13 cu. ft.)

300

190 – 300

56 – 90

4.20 – 6.75

Sewing Machine

75

4 – 14

0.3 – 1

0.02 – 0.08

Stereo

30

1 – 170

0.03 – 5.1

0.01 – 0.38

Television

180

60 – 440

5 – 35

0.38 – 2.63

Toaster

1150

1 – 3.5

1 – 4

0.08 – 0.30

Toothbrush

10

1 – 2

0.01 – 0.02

0.00

Vacuum Cleaner (Portable)

800

2 – 6

2 – 5

0.15 – 0.38

Video Cassette Recorder

40

50 – 200

1 – 8

0.08 – 0.60

Water Bed Heater

400

150 – 300

60 – 120

4.50 – 9.00

Water Heater Typical Family of 4

3800

98 – 138

375 – 525

28.13 – 39.38

Appliance Wattages

Appliance

Rated Watts

Surge Watts

Lighting

Sum of all standby lighting

Refrigerator / Freezer

500

2000

Sump Pump

800

2000

Water Pump (1/3 HP)

1000

3000

Furnace Fan (1/2 HP)

875

2300

Electric Blanket

400

400

Space Heater

1800

1800

Heat Pump

4700

12000

Dehumidifier

650

800

Attic Fan

300

900

Table Fan

800

2000

Window Air Conditioner

1200

4800

Central Air (10k BTU)

1500

6000

Central Air (24k BTU)

3800

15000

Central Air (40k BTU)

6000

24000

Computer

300

300

CD Player

100

100

VCR

100

100

Radio

100

100

Television

300

300

Receiver

420

420

Microwave

800

800

Blender

300

900

Coffee Maker

1500

1500

Electric Range (1 element)

1500

1500

Toaster (2-slice)

1000

1600

Dishwasher (Hot Dry)

1500

3000

Electric Oven

3400

3400

Iron

1200

1200

Washing Machine

1150

3400

Gas Clothes Dryer

700

2500

Electric Clothes Dryer

5400

6750

Security System

500

500

Deep Freezer

500

1000

Hair Dryer

1200

1200

Garage Door Opener (1/3 HP)

750

750

Electric Water Heater

4000

4000

Appliances and Approximate Wattages

Appliance

Wattage

Appliance

Wattage

Lighting – Basic

1,200 Watts

Lighting – Full

4,000 Watts

Electric Heat

5,000 Watts

Electric Water Heater

5,000 Watts

Refrigrator – 20 Cu Ft

800 Watts

Freezer – 20 Cu Ft

550 Watts

Sump Pump

900 Watts

Well Pump ½ HP

1,000 Watts

Well Pump 1HP

2,000 Watts

Garage Door Opener ½ HP

400 Watts

Microwave Oven 1000W

1,500 Watts

Dishwasher

400 Watts

Toaster

900 Watts

Computer

250 Watts

Electric Range Oven

7500 Watts

TV – 32" Color

170 Watts

VCR

60 Watts

Stereo System

140 Watts

Clothes Iron

1100 Watts

Electric Clothes Dryer

6000 Watts

Washing Machine

1000 Watts

Hair Dryer

1600 Watts

Air Conditioning 1 Ton

2,000 Watts

Air Conditioning 2 Ton

3,000 Watts

Air Conditioning 3 Ton

4,500 Watts

Window A/C

2000 Watts

Vacuum Cleaner

780 Watts

Central Vacuum

1750 Watts

Energy Use of Some Typical Home Appliances

If you want a general estimate of how much electricity your home appliances consume, you can refer to the list below, which provides the energy consumption (Wattage) of some typical home appliances. If you have appliances that are not listed in the table, or desire a more exact figure based on a specific appliance in your home, use the following formula to estimate the amount of energy a specific appliance consumes:

Multiply this by the number of days you use the appliance during the year for the annual consumption. You can then calculate the annual cost to run an appliance by multiplying the kWh per year by your local utility's rate per kWh consumed.

Examples:

Window fan

200 Watts * 4 hours/day * 120 days/year / 1000
= 96 kWh

96 kWh * 8.5 cents/kWh
= $8.16 / year

Personal Computer and Monitor

(120+150) Watts * 4 hours/day * 365 days/year / 1000
= 394 kWh

394 kWh * 8.5 cents/kWh
= $33.51/year

You can usually find the wattage of most appliances stamped on the bottom or back of the appliance, or on its "nameplate." The wattage listed is the maximum power drawn by the appliance. Since many appliances have a range of settings (for example, the volume on a radio), the actual amount of power consumed depends on the setting used at any one time.

Here are some examples of the range of nameplate wattages for various household appliances:

Refrigerators, although turned "on" all the time, actually cycle on and off at a rate that depends on a number of factors. These factors include how well it is insulated, room temperature, freezer temperature, how often the door is opened, if the coils are clean, if it is defrosted regularly, and the condition of the door seals. To get an approximate figure for the number of hours that a refrigerator actually operates at its maximum wattage, divide the total time the refrigerator is plugged in by three.

If the wattage is not listed on the appliance, you can still estimate it by finding the current draw (in amperes) and multiplying that by the voltage used by the appliance. Most appliances in the United States use 120 volts. Larger appliances, such as clothes dryers and electric cooktops, use 240 volts. The amperes might be stamped on the unit in place of the wattage. If not, find a clamp-on ammeter—an electrician's tool that clamps around one of the two wires on the appliance—to measure the current flowing through it. You can obtain this type of ammeter in stores that sell electrical and electronic equipment. Take a reading while the device is running; this is the actual amount of current being used at that instant.

Note: When measuring the current drawn by a motor, in the first second that the motor starts, the meter will show about three times the current than when it is running smoothly.

Also note that many appliances continue to draw a small amount of power when they are switched "off." These "phantom loads" occur in most appliances that use electricity, such as VCRs, televisions, stereos, computers, and kitchen appliances. Most phantom loads will increase the appliance's energy consumption a few watts per hour. These loads can be avoided by unplugging the appliance or using a power strip and using the switch on the power strip to cut all power to the appliance.

Appliance Wattage Hours/Month

Kitchen Appliances

Blender

Bread maker

Broiler

Can opener

Coffee maker

Cooktop/range

Crockpot

Dishwasher, heated dry cycle

Dishwasher, no dry cycle

Food processor

Freezer (approx. 16 cu.ft.)

Frying pan/skillet

Fryer, deep fat

Garbage disposal

Griddle

Ice cream maker

Ice crusher

Microwave oven

Mixer, hand-held

Mixer, stand

Oven, electric

Popcorn popper

Refrigerator, dorm size

Refrigerator/freezer, standard size

Roaster

Rotisserie

Toaster oven

Toaster, two-slice

Laundry Appliances

Clothes dryer, electric

Clothes washer

Iron

Personal Care

Curling iron

Electric blanket

Hair dryer

Heating pad

Indoor whirlpool tub

Outdoor hot tub

Shaver

Sun lamp/heat lamp

Waterbed heater, queen

Home Electronics

Computer

DVD

Fax machine

Radio or clock-radio

Stereo

Television, 13-inch

Television, 35-inch

VCR

Lighting

Compact fluorescent bulbs

Incandescent bulbs

Holiday lights, large

Holiday lighting, small

Outdoor lights, buglight

Outdoor lights, flood or spot

Outdoor lights, lamppost

Outdoor lights, porch light

Workshop/Garage

Belt sander

Circular saw

Disk sander

Drill

Electric lawn mower

Garage door opener

Hedge clipper

Saber saw/jigsaw

Soldering gun

Miscellaneous

Aquarium heater

Clock

Engine block heater

Sewing machine

Sump pump

Swimming pool pump

Vacuum cleaner

Vacuum, central system

Water heater, electric

Water softener

Well or water pump

Electricity Consumption Score Card

Appliances

Average Wattage

Average Hours per year

Est. KWH Used/Year

Cost Per Year (at 4 cents)

Comfort/Conditioning

Air Cleaner

50

4320

216

8.64

Air Conditioner*

860

1000

860

34.40

Air Conditioner*

3,750

1000

3750

150.00

Blanket

177

831

147

5.88

Dehumidifier

257

1467

377

15.08

Fan, Attic

370

786

291

11.64

Fan, Circulating

88

489

43

1.72

Fan, Rollaway

171

807

138

5.52

Fan, Window

200

850

170

6.80

Heat Lamp (infrared)

250

52

13

0.52

Heating Pad

65

154

10

0.40

Humidifier

177

921

163

6.52

Space Heater, portable

1,322

133

176

7.04

Lighting Fixtures
(Measure each light fixture separately, then add together. Lighting is said to account for one-fifth to one-fourth of the average electric bill.)